Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Federal and state operating loss carryforwards	$ 219,237	$ 172,530
Equity compensation	22,735	21,454
R&D tax credits, net of reserves	18,887	23,452
Disallowed interest	16,146	5,307
Temporary differences	7,695	5,054
Total deferred tax assets	284,700	227,797
Deferred tax liabilities:
Convertible debt	0	(24,795)
Other	(546)	(159)
Total deferred tax liabilities	(546)	(24,954)
Valuation allowance	(284,154)	(202,843)
Net deferred tax assets	$ 0	$ 0